Really, the argument that it's extra gear is a little spurious. A 2.5" drive is not that bulky, and unless you are carrying your iPad around in your hand everywhere you go, I'm sure you've got some kind of a case for it. It probably even has side pockets in it. But sure, if you've got $800 or $900 or more to throw around, then be my guest, you can have whatever you want. Most of the rest of us don't have that luxury, so in light of that I wouldn't mind the slight inconvenience of having to pack one extra piece of gear in my case. Before the iPad, it was my laptop, a much bulkier affair to be sure, so it's a matter of perspective, I guess.
I think the 'some instances' in which the pass-through wouldn't work that you refer to involve using the 4G cellular connection, but in most instances, who's going to use their data plan while streaming a huge movie file? For travel purposes, most airlines offer wi-fi, so for me this is not really an issue.
There is one thing that I would have liked to see included on the model I bought, however, and that is stereo speakers. I'm not sure why Apple opted to put a mono speaker in the iPad series when other tablet makers are selling models that do have stereo speakers. Maybe the 128 GB model will have that, as well.
The good thing is, we don't all have to agree on what to buy, because the market is offering us choices. There's no right or wrong purchase, except what works for the individual.
For me, I'm not interested in carrying around extra gear on the go, so 128GBs sounds great. Even more storage would be even better, as long as it fits my budget.